Release notes are available at https://www.openssh.com/txt/release-9.1 9.1 contains fixes for three minor memory safety problems; these have lready been merged to the copy of OpenSSH 9.0 that is in the FreeBSD base system. Some highlights copied from the release notes: Potentially-incompatible changes -------------------------------- * ssh(1), sshd(8): SetEnv directives in ssh_config and sshd_config are now first-match-wins to match other directives. Previously if an environment variable was multiply specified the last set value would have been used. bz3438 * ssh-keygen(8): ssh-keygen -A (generate all default host key types) will no longer generate DSA keys, as these are insecure and have not been used by default for some years. New features ------------ * ssh(1), sshd(8): add a RequiredRSASize directive to set a minimum RSA key length. Keys below this length will be ignored for user authentication and for host authentication in sshd(8). * sftp-server(8): add a "users-groups-by-id@openssh.com" extension request that allows the client to obtain user/group names that correspond to a set of uids/gids. * sftp(1): use "users-groups-by-id@openssh.com" sftp-server extension (when available) to fill in user/group names for directory listings. * sftp-server(8): support the "home-directory" extension request defined in draft-ietf-secsh-filexfer-extensions-00. This overlaps a bit with the existing "expand-path@openssh.com", but some other clients support it. * ssh-keygen(1), sshd(8): allow certificate validity intervals, sshsig verification times and authorized_keys expiry-time options to accept dates in the UTC time zone in addition to the default of interpreting them in the system time zone. YYYYMMDD and YYMMDDHHMM[SS] dates/times will be interpreted as UTC if suffixed with a 'Z' character. Also allow certificate validity intervals to be specified in raw seconds-since-epoch as hex value, e.g. -V 0x1234:0x4567890. This is intended for use by regress tests and other tools that call ssh-keygen as part of a CA workflow. bz3468 * sftp(1): allow arguments to the sftp -D option, e.g. sftp -D "/usr/libexec/sftp-server -el debug3" * ssh-keygen(1): allow the existing -U (use agent) flag to work with "-Y sign" operations, where it will be interpreted to require that the private keys is hosted in an agent; bz3429 MFC after: 2 weeks Relnotes: Yes Sponsored by: The FreeBSD Foundation
936 lines
28 KiB
C
936 lines
28 KiB
C
/* $OpenBSD: serverloop.c,v 1.232 2022/04/20 04:19:11 djm Exp $ */
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/*
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* Author: Tatu Ylonen <ylo@cs.hut.fi>
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* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
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* All rights reserved
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* Server main loop for handling the interactive session.
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*
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* As far as I am concerned, the code I have written for this software
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* can be used freely for any purpose. Any derived versions of this
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* software must be clearly marked as such, and if the derived work is
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* incompatible with the protocol description in the RFC file, it must be
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* called by a name other than "ssh" or "Secure Shell".
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*
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* SSH2 support by Markus Friedl.
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* Copyright (c) 2000, 2001 Markus Friedl. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "includes.h"
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#include <sys/types.h>
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#include <sys/wait.h>
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#include <sys/socket.h>
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#ifdef HAVE_SYS_TIME_H
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# include <sys/time.h>
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#endif
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#include <netinet/in.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <pwd.h>
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#include <limits.h>
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#ifdef HAVE_POLL_H
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#include <poll.h>
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#endif
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#include <signal.h>
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#include <string.h>
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#include <termios.h>
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#include <unistd.h>
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#include <stdarg.h>
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#include "openbsd-compat/sys-queue.h"
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#include "xmalloc.h"
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#include "packet.h"
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#include "sshbuf.h"
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#include "log.h"
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#include "misc.h"
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#include "servconf.h"
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#include "canohost.h"
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#include "sshpty.h"
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#include "channels.h"
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#include "compat.h"
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#include "ssh2.h"
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#include "sshkey.h"
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#include "cipher.h"
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#include "kex.h"
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#include "hostfile.h"
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#include "auth.h"
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#include "session.h"
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#include "dispatch.h"
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#include "auth-options.h"
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#include "serverloop.h"
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#include "ssherr.h"
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extern ServerOptions options;
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/* XXX */
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extern Authctxt *the_authctxt;
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extern struct sshauthopt *auth_opts;
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extern int use_privsep;
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static int no_more_sessions = 0; /* Disallow further sessions. */
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static volatile sig_atomic_t child_terminated = 0; /* The child has terminated. */
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/* Cleanup on signals (!use_privsep case only) */
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static volatile sig_atomic_t received_sigterm = 0;
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/* prototypes */
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static void server_init_dispatch(struct ssh *);
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/* requested tunnel forwarding interface(s), shared with session.c */
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char *tun_fwd_ifnames = NULL;
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/* returns 1 if bind to specified port by specified user is permitted */
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static int
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bind_permitted(int port, uid_t uid)
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{
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if (use_privsep)
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return 1; /* allow system to decide */
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if (port < IPPORT_RESERVED && uid != 0)
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return 0;
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return 1;
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}
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/*ARGSUSED*/
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static void
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sigchld_handler(int sig)
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{
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child_terminated = 1;
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}
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/*ARGSUSED*/
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static void
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sigterm_handler(int sig)
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{
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received_sigterm = sig;
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}
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static void
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client_alive_check(struct ssh *ssh)
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{
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char remote_id[512];
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int r, channel_id;
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/* timeout, check to see how many we have had */
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if (options.client_alive_count_max > 0 &&
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ssh_packet_inc_alive_timeouts(ssh) >
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options.client_alive_count_max) {
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sshpkt_fmt_connection_id(ssh, remote_id, sizeof(remote_id));
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logit("Timeout, client not responding from %s", remote_id);
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cleanup_exit(255);
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}
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/*
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* send a bogus global/channel request with "wantreply",
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* we should get back a failure
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*/
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if ((channel_id = channel_find_open(ssh)) == -1) {
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if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 ||
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(r = sshpkt_put_cstring(ssh, "keepalive@openssh.com"))
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!= 0 ||
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(r = sshpkt_put_u8(ssh, 1)) != 0) /* boolean: want reply */
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fatal_fr(r, "compose");
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} else {
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channel_request_start(ssh, channel_id,
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"keepalive@openssh.com", 1);
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}
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if ((r = sshpkt_send(ssh)) != 0)
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fatal_fr(r, "send");
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}
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/*
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* Sleep in ppoll() until we can do something.
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* Optionally, a maximum time can be specified for the duration of
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* the wait (0 = infinite).
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*/
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static void
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wait_until_can_do_something(struct ssh *ssh,
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int connection_in, int connection_out, struct pollfd **pfdp,
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u_int *npfd_allocp, u_int *npfd_activep, u_int64_t max_time_ms,
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sigset_t *sigsetp, int *conn_in_readyp, int *conn_out_readyp)
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{
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struct timespec ts, *tsp;
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int ret;
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time_t minwait_secs = 0;
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int client_alive_scheduled = 0;
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u_int p;
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/* time we last heard from the client OR sent a keepalive */
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static time_t last_client_time;
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*conn_in_readyp = *conn_out_readyp = 0;
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/* Prepare channel poll. First two pollfd entries are reserved */
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channel_prepare_poll(ssh, pfdp, npfd_allocp, npfd_activep,
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2, &minwait_secs);
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if (*npfd_activep < 2)
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fatal_f("bad npfd %u", *npfd_activep); /* shouldn't happen */
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/* XXX need proper deadline system for rekey/client alive */
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if (minwait_secs != 0)
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max_time_ms = MINIMUM(max_time_ms, (u_int)minwait_secs * 1000);
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/*
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* if using client_alive, set the max timeout accordingly,
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* and indicate that this particular timeout was for client
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* alive by setting the client_alive_scheduled flag.
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*
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* this could be randomized somewhat to make traffic
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* analysis more difficult, but we're not doing it yet.
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*/
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if (options.client_alive_interval) {
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uint64_t keepalive_ms =
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(uint64_t)options.client_alive_interval * 1000;
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if (max_time_ms == 0 || max_time_ms > keepalive_ms) {
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max_time_ms = keepalive_ms;
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client_alive_scheduled = 1;
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}
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if (last_client_time == 0)
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last_client_time = monotime();
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}
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#if 0
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/* wrong: bad condition XXX */
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if (channel_not_very_much_buffered_data())
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#endif
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/* Monitor client connection on reserved pollfd entries */
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(*pfdp)[0].fd = connection_in;
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(*pfdp)[0].events = POLLIN;
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(*pfdp)[1].fd = connection_out;
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(*pfdp)[1].events = ssh_packet_have_data_to_write(ssh) ? POLLOUT : 0;
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/*
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* If child has terminated and there is enough buffer space to read
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* from it, then read as much as is available and exit.
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*/
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if (child_terminated && ssh_packet_not_very_much_data_to_write(ssh))
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if (max_time_ms == 0 || client_alive_scheduled)
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max_time_ms = 100;
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if (max_time_ms == 0)
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tsp = NULL;
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else {
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ts.tv_sec = max_time_ms / 1000;
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ts.tv_nsec = 1000000 * (max_time_ms % 1000);
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tsp = &ts;
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}
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/* Wait for something to happen, or the timeout to expire. */
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ret = ppoll(*pfdp, *npfd_activep, tsp, sigsetp);
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if (ret == -1) {
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for (p = 0; p < *npfd_activep; p++)
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(*pfdp)[p].revents = 0;
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if (errno != EINTR)
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fatal_f("ppoll: %.100s", strerror(errno));
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return;
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}
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*conn_in_readyp = (*pfdp)[0].revents != 0;
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*conn_out_readyp = (*pfdp)[1].revents != 0;
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if (client_alive_scheduled) {
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time_t now = monotime();
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/*
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* If the ppoll timed out, or returned for some other reason
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* but we haven't heard from the client in time, send keepalive.
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*/
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if (ret == 0 || (last_client_time != 0 && last_client_time +
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options.client_alive_interval <= now)) {
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client_alive_check(ssh);
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last_client_time = now;
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} else if (*conn_in_readyp)
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last_client_time = now;
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}
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}
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/*
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* Processes input from the client and the program. Input data is stored
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* in buffers and processed later.
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*/
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static int
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process_input(struct ssh *ssh, int connection_in)
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{
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int r;
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if ((r = ssh_packet_process_read(ssh, connection_in)) == 0)
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return 0; /* success */
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if (r == SSH_ERR_SYSTEM_ERROR) {
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if (errno == EAGAIN || errno == EINTR || errno == EWOULDBLOCK)
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return 0;
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if (errno == EPIPE) {
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verbose("Connection closed by %.100s port %d",
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ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
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return -1;
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}
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verbose("Read error from remote host %s port %d: %s",
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ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
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strerror(errno));
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cleanup_exit(255);
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}
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return -1;
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}
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/*
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* Sends data from internal buffers to client program stdin.
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*/
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static void
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process_output(struct ssh *ssh, int connection_out)
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{
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int r;
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/* Send any buffered packet data to the client. */
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if ((r = ssh_packet_write_poll(ssh)) != 0) {
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sshpkt_fatal(ssh, r, "%s: ssh_packet_write_poll",
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__func__);
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}
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}
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static void
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process_buffered_input_packets(struct ssh *ssh)
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{
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ssh_dispatch_run_fatal(ssh, DISPATCH_NONBLOCK, NULL);
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}
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static void
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collect_children(struct ssh *ssh)
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{
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pid_t pid;
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int status;
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if (child_terminated) {
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debug("Received SIGCHLD.");
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while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
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(pid == -1 && errno == EINTR))
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if (pid > 0)
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session_close_by_pid(ssh, pid, status);
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child_terminated = 0;
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}
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}
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void
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server_loop2(struct ssh *ssh, Authctxt *authctxt)
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{
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struct pollfd *pfd = NULL;
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u_int npfd_alloc = 0, npfd_active = 0;
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int r, conn_in_ready, conn_out_ready;
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u_int connection_in, connection_out;
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u_int64_t rekey_timeout_ms = 0;
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sigset_t bsigset, osigset;
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debug("Entering interactive session for SSH2.");
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if (sigemptyset(&bsigset) == -1 || sigaddset(&bsigset, SIGCHLD) == -1)
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error_f("bsigset setup: %s", strerror(errno));
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ssh_signal(SIGCHLD, sigchld_handler);
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child_terminated = 0;
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connection_in = ssh_packet_get_connection_in(ssh);
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connection_out = ssh_packet_get_connection_out(ssh);
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if (!use_privsep) {
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ssh_signal(SIGTERM, sigterm_handler);
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ssh_signal(SIGINT, sigterm_handler);
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ssh_signal(SIGQUIT, sigterm_handler);
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}
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server_init_dispatch(ssh);
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for (;;) {
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process_buffered_input_packets(ssh);
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if (!ssh_packet_is_rekeying(ssh) &&
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ssh_packet_not_very_much_data_to_write(ssh))
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channel_output_poll(ssh);
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if (options.rekey_interval > 0 &&
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!ssh_packet_is_rekeying(ssh)) {
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rekey_timeout_ms = ssh_packet_get_rekey_timeout(ssh) *
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1000;
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} else {
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rekey_timeout_ms = 0;
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}
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|
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/*
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* Block SIGCHLD while we check for dead children, then pass
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* the old signal mask through to ppoll() so that it'll wake
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* up immediately if a child exits after we've called waitpid().
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*/
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if (sigprocmask(SIG_BLOCK, &bsigset, &osigset) == -1)
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error_f("bsigset sigprocmask: %s", strerror(errno));
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collect_children(ssh);
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wait_until_can_do_something(ssh, connection_in, connection_out,
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&pfd, &npfd_alloc, &npfd_active, rekey_timeout_ms, &osigset,
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&conn_in_ready, &conn_out_ready);
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if (sigprocmask(SIG_UNBLOCK, &bsigset, &osigset) == -1)
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error_f("osigset sigprocmask: %s", strerror(errno));
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|
|
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if (received_sigterm) {
|
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logit("Exiting on signal %d", (int)received_sigterm);
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/* Clean up sessions, utmp, etc. */
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cleanup_exit(255);
|
|
}
|
|
|
|
channel_after_poll(ssh, pfd, npfd_active);
|
|
if (conn_in_ready &&
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process_input(ssh, connection_in) < 0)
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|
break;
|
|
/* A timeout may have triggered rekeying */
|
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if ((r = ssh_packet_check_rekey(ssh)) != 0)
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fatal_fr(r, "cannot start rekeying");
|
|
if (conn_out_ready)
|
|
process_output(ssh, connection_out);
|
|
}
|
|
collect_children(ssh);
|
|
free(pfd);
|
|
|
|
/* free all channels, no more reads and writes */
|
|
channel_free_all(ssh);
|
|
|
|
/* free remaining sessions, e.g. remove wtmp entries */
|
|
session_destroy_all(ssh, NULL);
|
|
}
|
|
|
|
static int
|
|
server_input_keep_alive(int type, u_int32_t seq, struct ssh *ssh)
|
|
{
|
|
debug("Got %d/%u for keepalive", type, seq);
|
|
/*
|
|
* reset timeout, since we got a sane answer from the client.
|
|
* even if this was generated by something other than
|
|
* the bogus CHANNEL_REQUEST we send for keepalives.
|
|
*/
|
|
ssh_packet_set_alive_timeouts(ssh, 0);
|
|
return 0;
|
|
}
|
|
|
|
static Channel *
|
|
server_request_direct_tcpip(struct ssh *ssh, int *reason, const char **errmsg)
|
|
{
|
|
Channel *c = NULL;
|
|
char *target = NULL, *originator = NULL;
|
|
u_int target_port = 0, originator_port = 0;
|
|
int r;
|
|
|
|
if ((r = sshpkt_get_cstring(ssh, &target, NULL)) != 0 ||
|
|
(r = sshpkt_get_u32(ssh, &target_port)) != 0 ||
|
|
(r = sshpkt_get_cstring(ssh, &originator, NULL)) != 0 ||
|
|
(r = sshpkt_get_u32(ssh, &originator_port)) != 0 ||
|
|
(r = sshpkt_get_end(ssh)) != 0)
|
|
sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
|
|
if (target_port > 0xFFFF) {
|
|
error_f("invalid target port");
|
|
*reason = SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED;
|
|
goto out;
|
|
}
|
|
if (originator_port > 0xFFFF) {
|
|
error_f("invalid originator port");
|
|
*reason = SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED;
|
|
goto out;
|
|
}
|
|
|
|
debug_f("originator %s port %u, target %s port %u",
|
|
originator, originator_port, target, target_port);
|
|
|
|
/* XXX fine grained permissions */
|
|
if ((options.allow_tcp_forwarding & FORWARD_LOCAL) != 0 &&
|
|
auth_opts->permit_port_forwarding_flag &&
|
|
!options.disable_forwarding) {
|
|
c = channel_connect_to_port(ssh, target, target_port,
|
|
"direct-tcpip", "direct-tcpip", reason, errmsg);
|
|
} else {
|
|
logit("refused local port forward: "
|
|
"originator %s port %d, target %s port %d",
|
|
originator, originator_port, target, target_port);
|
|
if (reason != NULL)
|
|
*reason = SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED;
|
|
}
|
|
|
|
out:
|
|
free(originator);
|
|
free(target);
|
|
return c;
|
|
}
|
|
|
|
static Channel *
|
|
server_request_direct_streamlocal(struct ssh *ssh)
|
|
{
|
|
Channel *c = NULL;
|
|
char *target = NULL, *originator = NULL;
|
|
u_int originator_port = 0;
|
|
struct passwd *pw = the_authctxt->pw;
|
|
int r;
|
|
|
|
if (pw == NULL || !the_authctxt->valid)
|
|
fatal_f("no/invalid user");
|
|
|
|
if ((r = sshpkt_get_cstring(ssh, &target, NULL)) != 0 ||
|
|
(r = sshpkt_get_cstring(ssh, &originator, NULL)) != 0 ||
|
|
(r = sshpkt_get_u32(ssh, &originator_port)) != 0 ||
|
|
(r = sshpkt_get_end(ssh)) != 0)
|
|
sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
|
|
if (originator_port > 0xFFFF) {
|
|
error_f("invalid originator port");
|
|
goto out;
|
|
}
|
|
|
|
debug_f("originator %s port %d, target %s",
|
|
originator, originator_port, target);
|
|
|
|
/* XXX fine grained permissions */
|
|
if ((options.allow_streamlocal_forwarding & FORWARD_LOCAL) != 0 &&
|
|
auth_opts->permit_port_forwarding_flag &&
|
|
!options.disable_forwarding && (pw->pw_uid == 0 || use_privsep)) {
|
|
c = channel_connect_to_path(ssh, target,
|
|
"direct-streamlocal@openssh.com", "direct-streamlocal");
|
|
} else {
|
|
logit("refused streamlocal port forward: "
|
|
"originator %s port %d, target %s",
|
|
originator, originator_port, target);
|
|
}
|
|
|
|
out:
|
|
free(originator);
|
|
free(target);
|
|
return c;
|
|
}
|
|
|
|
static Channel *
|
|
server_request_tun(struct ssh *ssh)
|
|
{
|
|
Channel *c = NULL;
|
|
u_int mode, tun;
|
|
int r, sock;
|
|
char *tmp, *ifname = NULL;
|
|
|
|
if ((r = sshpkt_get_u32(ssh, &mode)) != 0)
|
|
sshpkt_fatal(ssh, r, "%s: parse mode", __func__);
|
|
switch (mode) {
|
|
case SSH_TUNMODE_POINTOPOINT:
|
|
case SSH_TUNMODE_ETHERNET:
|
|
break;
|
|
default:
|
|
ssh_packet_send_debug(ssh, "Unsupported tunnel device mode.");
|
|
return NULL;
|
|
}
|
|
if ((options.permit_tun & mode) == 0) {
|
|
ssh_packet_send_debug(ssh, "Server has rejected tunnel device "
|
|
"forwarding");
|
|
return NULL;
|
|
}
|
|
|
|
if ((r = sshpkt_get_u32(ssh, &tun)) != 0)
|
|
sshpkt_fatal(ssh, r, "%s: parse device", __func__);
|
|
if (tun > INT_MAX) {
|
|
debug_f("invalid tun");
|
|
goto done;
|
|
}
|
|
if (auth_opts->force_tun_device != -1) {
|
|
if (tun != SSH_TUNID_ANY &&
|
|
auth_opts->force_tun_device != (int)tun)
|
|
goto done;
|
|
tun = auth_opts->force_tun_device;
|
|
}
|
|
sock = tun_open(tun, mode, &ifname);
|
|
if (sock < 0)
|
|
goto done;
|
|
debug("Tunnel forwarding using interface %s", ifname);
|
|
|
|
c = channel_new(ssh, "tun", SSH_CHANNEL_OPEN, sock, sock, -1,
|
|
CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1);
|
|
c->datagram = 1;
|
|
#if defined(SSH_TUN_FILTER)
|
|
if (mode == SSH_TUNMODE_POINTOPOINT)
|
|
channel_register_filter(ssh, c->self, sys_tun_infilter,
|
|
sys_tun_outfilter, NULL, NULL);
|
|
#endif
|
|
|
|
/*
|
|
* Update the list of names exposed to the session
|
|
* XXX remove these if the tunnels are closed (won't matter
|
|
* much if they are already in the environment though)
|
|
*/
|
|
tmp = tun_fwd_ifnames;
|
|
xasprintf(&tun_fwd_ifnames, "%s%s%s",
|
|
tun_fwd_ifnames == NULL ? "" : tun_fwd_ifnames,
|
|
tun_fwd_ifnames == NULL ? "" : ",",
|
|
ifname);
|
|
free(tmp);
|
|
free(ifname);
|
|
|
|
done:
|
|
if (c == NULL)
|
|
ssh_packet_send_debug(ssh, "Failed to open the tunnel device.");
|
|
return c;
|
|
}
|
|
|
|
static Channel *
|
|
server_request_session(struct ssh *ssh)
|
|
{
|
|
Channel *c;
|
|
int r;
|
|
|
|
debug("input_session_request");
|
|
if ((r = sshpkt_get_end(ssh)) != 0)
|
|
sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
|
|
|
|
if (no_more_sessions) {
|
|
ssh_packet_disconnect(ssh, "Possible attack: attempt to open a "
|
|
"session after additional sessions disabled");
|
|
}
|
|
|
|
/*
|
|
* A server session has no fd to read or write until a
|
|
* CHANNEL_REQUEST for a shell is made, so we set the type to
|
|
* SSH_CHANNEL_LARVAL. Additionally, a callback for handling all
|
|
* CHANNEL_REQUEST messages is registered.
|
|
*/
|
|
c = channel_new(ssh, "session", SSH_CHANNEL_LARVAL,
|
|
-1, -1, -1, /*window size*/0, CHAN_SES_PACKET_DEFAULT,
|
|
0, "server-session", 1);
|
|
if (session_open(the_authctxt, c->self) != 1) {
|
|
debug("session open failed, free channel %d", c->self);
|
|
channel_free(ssh, c);
|
|
return NULL;
|
|
}
|
|
channel_register_cleanup(ssh, c->self, session_close_by_channel, 0);
|
|
return c;
|
|
}
|
|
|
|
static int
|
|
server_input_channel_open(int type, u_int32_t seq, struct ssh *ssh)
|
|
{
|
|
Channel *c = NULL;
|
|
char *ctype = NULL;
|
|
const char *errmsg = NULL;
|
|
int r, reason = SSH2_OPEN_CONNECT_FAILED;
|
|
u_int rchan = 0, rmaxpack = 0, rwindow = 0;
|
|
|
|
if ((r = sshpkt_get_cstring(ssh, &ctype, NULL)) != 0 ||
|
|
(r = sshpkt_get_u32(ssh, &rchan)) != 0 ||
|
|
(r = sshpkt_get_u32(ssh, &rwindow)) != 0 ||
|
|
(r = sshpkt_get_u32(ssh, &rmaxpack)) != 0)
|
|
sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
|
|
debug_f("ctype %s rchan %u win %u max %u",
|
|
ctype, rchan, rwindow, rmaxpack);
|
|
|
|
if (strcmp(ctype, "session") == 0) {
|
|
c = server_request_session(ssh);
|
|
} else if (strcmp(ctype, "direct-tcpip") == 0) {
|
|
c = server_request_direct_tcpip(ssh, &reason, &errmsg);
|
|
} else if (strcmp(ctype, "direct-streamlocal@openssh.com") == 0) {
|
|
c = server_request_direct_streamlocal(ssh);
|
|
} else if (strcmp(ctype, "tun@openssh.com") == 0) {
|
|
c = server_request_tun(ssh);
|
|
}
|
|
if (c != NULL) {
|
|
debug_f("confirm %s", ctype);
|
|
c->remote_id = rchan;
|
|
c->have_remote_id = 1;
|
|
c->remote_window = rwindow;
|
|
c->remote_maxpacket = rmaxpack;
|
|
if (c->type != SSH_CHANNEL_CONNECTING) {
|
|
if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN_CONFIRMATION)) != 0 ||
|
|
(r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
|
|
(r = sshpkt_put_u32(ssh, c->self)) != 0 ||
|
|
(r = sshpkt_put_u32(ssh, c->local_window)) != 0 ||
|
|
(r = sshpkt_put_u32(ssh, c->local_maxpacket)) != 0 ||
|
|
(r = sshpkt_send(ssh)) != 0) {
|
|
sshpkt_fatal(ssh, r,
|
|
"%s: send open confirm", __func__);
|
|
}
|
|
}
|
|
} else {
|
|
debug_f("failure %s", ctype);
|
|
if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN_FAILURE)) != 0 ||
|
|
(r = sshpkt_put_u32(ssh, rchan)) != 0 ||
|
|
(r = sshpkt_put_u32(ssh, reason)) != 0 ||
|
|
(r = sshpkt_put_cstring(ssh, errmsg ? errmsg : "open failed")) != 0 ||
|
|
(r = sshpkt_put_cstring(ssh, "")) != 0 ||
|
|
(r = sshpkt_send(ssh)) != 0) {
|
|
sshpkt_fatal(ssh, r,
|
|
"%s: send open failure", __func__);
|
|
}
|
|
}
|
|
free(ctype);
|
|
return 0;
|
|
}
|
|
|
|
static int
|
|
server_input_hostkeys_prove(struct ssh *ssh, struct sshbuf **respp)
|
|
{
|
|
struct sshbuf *resp = NULL;
|
|
struct sshbuf *sigbuf = NULL;
|
|
struct sshkey *key = NULL, *key_pub = NULL, *key_prv = NULL;
|
|
int r, ndx, success = 0;
|
|
const u_char *blob;
|
|
const char *sigalg, *kex_rsa_sigalg = NULL;
|
|
u_char *sig = 0;
|
|
size_t blen, slen;
|
|
|
|
if ((resp = sshbuf_new()) == NULL || (sigbuf = sshbuf_new()) == NULL)
|
|
fatal_f("sshbuf_new");
|
|
if (sshkey_type_plain(sshkey_type_from_name(
|
|
ssh->kex->hostkey_alg)) == KEY_RSA)
|
|
kex_rsa_sigalg = ssh->kex->hostkey_alg;
|
|
while (ssh_packet_remaining(ssh) > 0) {
|
|
sshkey_free(key);
|
|
key = NULL;
|
|
if ((r = sshpkt_get_string_direct(ssh, &blob, &blen)) != 0 ||
|
|
(r = sshkey_from_blob(blob, blen, &key)) != 0) {
|
|
error_fr(r, "parse key");
|
|
goto out;
|
|
}
|
|
/*
|
|
* Better check that this is actually one of our hostkeys
|
|
* before attempting to sign anything with it.
|
|
*/
|
|
if ((ndx = ssh->kex->host_key_index(key, 1, ssh)) == -1) {
|
|
error_f("unknown host %s key", sshkey_type(key));
|
|
goto out;
|
|
}
|
|
/*
|
|
* XXX refactor: make kex->sign just use an index rather
|
|
* than passing in public and private keys
|
|
*/
|
|
if ((key_prv = get_hostkey_by_index(ndx)) == NULL &&
|
|
(key_pub = get_hostkey_public_by_index(ndx, ssh)) == NULL) {
|
|
error_f("can't retrieve hostkey %d", ndx);
|
|
goto out;
|
|
}
|
|
sshbuf_reset(sigbuf);
|
|
free(sig);
|
|
sig = NULL;
|
|
/*
|
|
* For RSA keys, prefer to use the signature type negotiated
|
|
* during KEX to the default (SHA1).
|
|
*/
|
|
sigalg = NULL;
|
|
if (sshkey_type_plain(key->type) == KEY_RSA) {
|
|
if (kex_rsa_sigalg != NULL)
|
|
sigalg = kex_rsa_sigalg;
|
|
else if (ssh->kex->flags & KEX_RSA_SHA2_512_SUPPORTED)
|
|
sigalg = "rsa-sha2-512";
|
|
else if (ssh->kex->flags & KEX_RSA_SHA2_256_SUPPORTED)
|
|
sigalg = "rsa-sha2-256";
|
|
}
|
|
debug3_f("sign %s key (index %d) using sigalg %s",
|
|
sshkey_type(key), ndx, sigalg == NULL ? "default" : sigalg);
|
|
if ((r = sshbuf_put_cstring(sigbuf,
|
|
"hostkeys-prove-00@openssh.com")) != 0 ||
|
|
(r = sshbuf_put_stringb(sigbuf,
|
|
ssh->kex->session_id)) != 0 ||
|
|
(r = sshkey_puts(key, sigbuf)) != 0 ||
|
|
(r = ssh->kex->sign(ssh, key_prv, key_pub, &sig, &slen,
|
|
sshbuf_ptr(sigbuf), sshbuf_len(sigbuf), sigalg)) != 0 ||
|
|
(r = sshbuf_put_string(resp, sig, slen)) != 0) {
|
|
error_fr(r, "assemble signature");
|
|
goto out;
|
|
}
|
|
}
|
|
/* Success */
|
|
*respp = resp;
|
|
resp = NULL; /* don't free it */
|
|
success = 1;
|
|
out:
|
|
free(sig);
|
|
sshbuf_free(resp);
|
|
sshbuf_free(sigbuf);
|
|
sshkey_free(key);
|
|
return success;
|
|
}
|
|
|
|
static int
|
|
server_input_global_request(int type, u_int32_t seq, struct ssh *ssh)
|
|
{
|
|
char *rtype = NULL;
|
|
u_char want_reply = 0;
|
|
int r, success = 0, allocated_listen_port = 0;
|
|
u_int port = 0;
|
|
struct sshbuf *resp = NULL;
|
|
struct passwd *pw = the_authctxt->pw;
|
|
struct Forward fwd;
|
|
|
|
memset(&fwd, 0, sizeof(fwd));
|
|
if (pw == NULL || !the_authctxt->valid)
|
|
fatal_f("no/invalid user");
|
|
|
|
if ((r = sshpkt_get_cstring(ssh, &rtype, NULL)) != 0 ||
|
|
(r = sshpkt_get_u8(ssh, &want_reply)) != 0)
|
|
sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
|
|
debug_f("rtype %s want_reply %d", rtype, want_reply);
|
|
|
|
/* -R style forwarding */
|
|
if (strcmp(rtype, "tcpip-forward") == 0) {
|
|
if ((r = sshpkt_get_cstring(ssh, &fwd.listen_host, NULL)) != 0 ||
|
|
(r = sshpkt_get_u32(ssh, &port)) != 0)
|
|
sshpkt_fatal(ssh, r, "%s: parse tcpip-forward", __func__);
|
|
debug_f("tcpip-forward listen %s port %u",
|
|
fwd.listen_host, port);
|
|
if (port <= INT_MAX)
|
|
fwd.listen_port = (int)port;
|
|
/* check permissions */
|
|
if (port > INT_MAX ||
|
|
(options.allow_tcp_forwarding & FORWARD_REMOTE) == 0 ||
|
|
!auth_opts->permit_port_forwarding_flag ||
|
|
options.disable_forwarding ||
|
|
(!want_reply && fwd.listen_port == 0) ||
|
|
(fwd.listen_port != 0 &&
|
|
!bind_permitted(fwd.listen_port, pw->pw_uid))) {
|
|
success = 0;
|
|
ssh_packet_send_debug(ssh, "Server has disabled port forwarding.");
|
|
} else {
|
|
/* Start listening on the port */
|
|
success = channel_setup_remote_fwd_listener(ssh, &fwd,
|
|
&allocated_listen_port, &options.fwd_opts);
|
|
}
|
|
if ((resp = sshbuf_new()) == NULL)
|
|
fatal_f("sshbuf_new");
|
|
if (allocated_listen_port != 0 &&
|
|
(r = sshbuf_put_u32(resp, allocated_listen_port)) != 0)
|
|
fatal_fr(r, "sshbuf_put_u32");
|
|
} else if (strcmp(rtype, "cancel-tcpip-forward") == 0) {
|
|
if ((r = sshpkt_get_cstring(ssh, &fwd.listen_host, NULL)) != 0 ||
|
|
(r = sshpkt_get_u32(ssh, &port)) != 0)
|
|
sshpkt_fatal(ssh, r, "%s: parse cancel-tcpip-forward", __func__);
|
|
|
|
debug_f("cancel-tcpip-forward addr %s port %d",
|
|
fwd.listen_host, port);
|
|
if (port <= INT_MAX) {
|
|
fwd.listen_port = (int)port;
|
|
success = channel_cancel_rport_listener(ssh, &fwd);
|
|
}
|
|
} else if (strcmp(rtype, "streamlocal-forward@openssh.com") == 0) {
|
|
if ((r = sshpkt_get_cstring(ssh, &fwd.listen_path, NULL)) != 0)
|
|
sshpkt_fatal(ssh, r, "%s: parse streamlocal-forward@openssh.com", __func__);
|
|
debug_f("streamlocal-forward listen path %s",
|
|
fwd.listen_path);
|
|
|
|
/* check permissions */
|
|
if ((options.allow_streamlocal_forwarding & FORWARD_REMOTE) == 0
|
|
|| !auth_opts->permit_port_forwarding_flag ||
|
|
options.disable_forwarding ||
|
|
(pw->pw_uid != 0 && !use_privsep)) {
|
|
success = 0;
|
|
ssh_packet_send_debug(ssh, "Server has disabled "
|
|
"streamlocal forwarding.");
|
|
} else {
|
|
/* Start listening on the socket */
|
|
success = channel_setup_remote_fwd_listener(ssh,
|
|
&fwd, NULL, &options.fwd_opts);
|
|
}
|
|
} else if (strcmp(rtype, "cancel-streamlocal-forward@openssh.com") == 0) {
|
|
if ((r = sshpkt_get_cstring(ssh, &fwd.listen_path, NULL)) != 0)
|
|
sshpkt_fatal(ssh, r, "%s: parse cancel-streamlocal-forward@openssh.com", __func__);
|
|
debug_f("cancel-streamlocal-forward path %s",
|
|
fwd.listen_path);
|
|
|
|
success = channel_cancel_rport_listener(ssh, &fwd);
|
|
} else if (strcmp(rtype, "no-more-sessions@openssh.com") == 0) {
|
|
no_more_sessions = 1;
|
|
success = 1;
|
|
} else if (strcmp(rtype, "hostkeys-prove-00@openssh.com") == 0) {
|
|
success = server_input_hostkeys_prove(ssh, &resp);
|
|
}
|
|
/* XXX sshpkt_get_end() */
|
|
if (want_reply) {
|
|
if ((r = sshpkt_start(ssh, success ?
|
|
SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE)) != 0 ||
|
|
(success && resp != NULL && (r = sshpkt_putb(ssh, resp)) != 0) ||
|
|
(r = sshpkt_send(ssh)) != 0 ||
|
|
(r = ssh_packet_write_wait(ssh)) != 0)
|
|
sshpkt_fatal(ssh, r, "%s: send reply", __func__);
|
|
}
|
|
free(fwd.listen_host);
|
|
free(fwd.listen_path);
|
|
free(rtype);
|
|
sshbuf_free(resp);
|
|
return 0;
|
|
}
|
|
|
|
static int
|
|
server_input_channel_req(int type, u_int32_t seq, struct ssh *ssh)
|
|
{
|
|
Channel *c;
|
|
int r, success = 0;
|
|
char *rtype = NULL;
|
|
u_char want_reply = 0;
|
|
u_int id = 0;
|
|
|
|
if ((r = sshpkt_get_u32(ssh, &id)) != 0 ||
|
|
(r = sshpkt_get_cstring(ssh, &rtype, NULL)) != 0 ||
|
|
(r = sshpkt_get_u8(ssh, &want_reply)) != 0)
|
|
sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
|
|
|
|
debug("server_input_channel_req: channel %u request %s reply %d",
|
|
id, rtype, want_reply);
|
|
|
|
if (id >= INT_MAX || (c = channel_lookup(ssh, (int)id)) == NULL) {
|
|
ssh_packet_disconnect(ssh, "%s: unknown channel %d",
|
|
__func__, id);
|
|
}
|
|
if (!strcmp(rtype, "eow@openssh.com")) {
|
|
if ((r = sshpkt_get_end(ssh)) != 0)
|
|
sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
|
|
chan_rcvd_eow(ssh, c);
|
|
} else if ((c->type == SSH_CHANNEL_LARVAL ||
|
|
c->type == SSH_CHANNEL_OPEN) && strcmp(c->ctype, "session") == 0)
|
|
success = session_input_channel_req(ssh, c, rtype);
|
|
if (want_reply && !(c->flags & CHAN_CLOSE_SENT)) {
|
|
if (!c->have_remote_id)
|
|
fatal_f("channel %d: no remote_id", c->self);
|
|
if ((r = sshpkt_start(ssh, success ?
|
|
SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE)) != 0 ||
|
|
(r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
|
|
(r = sshpkt_send(ssh)) != 0)
|
|
sshpkt_fatal(ssh, r, "%s: send reply", __func__);
|
|
}
|
|
free(rtype);
|
|
return 0;
|
|
}
|
|
|
|
static void
|
|
server_init_dispatch(struct ssh *ssh)
|
|
{
|
|
debug("server_init_dispatch");
|
|
ssh_dispatch_init(ssh, &dispatch_protocol_error);
|
|
ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose);
|
|
ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_DATA, &channel_input_data);
|
|
ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_EOF, &channel_input_ieof);
|
|
ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data);
|
|
ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN, &server_input_channel_open);
|
|
ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation);
|
|
ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure);
|
|
ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_REQUEST, &server_input_channel_req);
|
|
ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust);
|
|
ssh_dispatch_set(ssh, SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request);
|
|
/* client_alive */
|
|
ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_SUCCESS, &server_input_keep_alive);
|
|
ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_FAILURE, &server_input_keep_alive);
|
|
ssh_dispatch_set(ssh, SSH2_MSG_REQUEST_SUCCESS, &server_input_keep_alive);
|
|
ssh_dispatch_set(ssh, SSH2_MSG_REQUEST_FAILURE, &server_input_keep_alive);
|
|
/* rekeying */
|
|
ssh_dispatch_set(ssh, SSH2_MSG_KEXINIT, &kex_input_kexinit);
|
|
}
|